1. Field of the Invention
The invention relates generally to a process for recognizing abnormal combustions in the cylinder of an internal-combustion engine.
2. Description of the Related Art
U.S. Pat. No. 4,697,561 discloses a method in which the speeds for each cylinder are detected, during its work cycle, by means of the crankshaft positions in which the crankshaft is at the lowest and the highest speed respectively. The difference between these two speeds is a measure of the torque generated by the cylinder. This, when related to the averaged torque of all the cylinders, gives an indication of the operating efficiency of the cylinder in question, which is utilized for diagnostic purposes.
In this method, the crankshaft positions having the lowest and the highest crankshaft speed have to be determined experimentally on the engine test bench. In particular, they are dependent on the load and on the speed and are stored in this dependence in the control unit for carrying out the method.
Corresponding tests on the engine test bench have shown that it is difficult to fix these crankshaft positions. Particularly for the purposes of the diagnosis of abnormal combustions, it has not been possible, in specific load and speed ranges, to find any crankshaft positions which would give a speed-difference signal which can be evaluated with sufficient accuracy.